ABSTRACT Luminescent manometry enables noncontact pressure sensing at small scales and under extreme conditions, yet its development remains constrained by the limited sensitivity and single‐mode response of commercial materials, as well as the absence of a comprehensive theoretical framework for pressure induced spectral evolution. To address these challenges, we selectively chose the Sr 3 Al 2 Ge 4 O 14 host where the cation disorder stabilizes multiple nonequivalent Cr 3+ centers, producing coexisting narrow‐line and broadband emissions across 0–10.06 GPa. This coexistence of narrow‐line and broadband emissions provides multiple complementary readout channels based on spectral shifts and luminescence intensity ratios, indicating the potential of this phosphor for multimodal pressure readout under compression. Ab initio calculations of pressure dependent excited states produce configurational coordinate diagrams that clearly reveal how compression perturbs excited state energies and alters equilibrium Cr─O bond lengths. These insights rationalize the opposite pressure shifts of narrow line and broadband emissions and their intensity variations. Crucially, a correlation between excitation‐induced bond length changes and pressure dependent spectral shifts was identified, showing that direction and magnitude of structural response upon excitation govern high pressure luminescence. This combined experimental‐theoretical study provides mechanistic insight into pressure‑dependent Cr 3+ luminescence and a framework that may guide the development of improved optical pressure probes.

We report the valence-to-core resonant inelastic x-ray scattering (RIXS) of EuS measured at the L3 edge of Eu. The obtained data reveal two sets of excitations: one set is composed of a hole in the S 3p bands and an electron excited to extended Eu 5d band states, the other is made up from a hole in the Eu 4f states and an electron in localized Eu 5d states bound to the 4f hole by its Coulomb potential. The delocalized excitations arise from the dipole-allowed 5d to 2p emissions, whereas the localized excitations result from the dipole-forbidden (quadrupole-allowed) 4f to 2p emissions. Both these emission channels have a comparable intensity thanks to a small number of occupied 5d states (approximately 0.6) combined with a large number of occupied 4f states (seven). We identify the localized electron-hole pairs with the "magnetic excitons" suggested in the past as an interpretation of the sharp features seen in the optical absorption spectra. Our observations provide a direct experimental evidence of these excitons which has been missing up to now.

In this work, the absorption spectra of metastable Dy2+, Nd2+, and Sm2+ are identified in SrAl2O4:Eu,Ln persistent phosphors after excitation with blue light, thereby confirming that the persistent luminescence is indeed due to a charge transfer between the two lanthanide dopants. In contrast to previous studies relying on X-ray absorption spectroscopy to observe charge transfers between dopants, here low-energy light is exclusively employed to probe for changes in the absorption spectrum of the phosphor, thereby only minimally affecting the state of the phosphor. Optical bleaching in combination with thermoluminescence measurements allowed to assign which optically active trapping centers contribute to the afterglow of the persistent phosphors.

This Tutorial article focuses on magnetic phenomena and material systems that have gained significant importance since the original development of mumax3, but are challenging to simulate for users who rely solely on the originally provided examples. Alongside the physical background, we provide hands-on examples of advanced magnetic systems, including detailed explanations of complete mumax3 input files (13 in total, often showing different ways to achieve things), and highlighting potential pitfalls where applicable. Specifically, we explore two approaches to incorporate spin–orbit torques in mumax simulations, considering the trade-off between versatility and speed. We also examine complex multilayer material stacks, including synthetic antiferromagnets, demonstrating different implementation methods that again vary in speed, versatility, and realism. A key criterion for selecting the optimal simulation strategy is its suitability for modeling systems where the magnetization varies significantly in the third dimension. The material covered in this Tutorial paper includes content developed for the mumax3 workshop presented during the summer of 2020 within the context of the IEEE online spintronics seminar, along with additional new topics. Throughout the explanations, we ensure broad applicability beyond specific examples.

Despite the development of many luminescent materials for various applications, only a few of these phosphors are applicable for solar energy generation applications. This study used the conventional solid-state reaction method to synthesize different strontium borate compounds codoped with divalent europium and samarium ions. The material was optimized by varying the experimental procedure, the molar ratio of the boron, and the molar ratios of both codopants. Strontium hexaborate doped with a relatively high europium concentration and a low samarium concentration (Sr0.89B6O10:Eu0.1 , Sm0.01) gave the optimum optical properties. These properties included a broad excitation range from 220 to 600 nm containing contributions from divalent europium and samarium ions. The material exhibited strong and narrow emission in the region from 650 to 850 nm following radiative transitions within the divalent samarium ions. The internal luminescence quantum efficiency of the optimized material was 79% (lambda ex = 508.5 nm). There was no spectral overlap between the excitation and emission spectra, thereby reducing the reabsorption probability. These marked characteristics make this phosphor material appropriate for use as a solar radiation converter or for use in luminescent solar concentrators.

The green-emitting SrAl2O4:Eu,Dy phosphor is the most widely used and well-studied persistent luminescent phosphor available today. Recent efforts to boost its performance in terms of luminescence intensity and duration are challenged by complex loss mechanisms, including the optically stimulated release of previously trapped charges by excitation light. Here, we present minimally scattering SrAl2O4:Eu,Dy single crystals, which, as opposed to powder phosphors, allow to profit from a so-called volume effect, resulting in a significantly increased emission intensity. Additionally, they allow for the identification of the reabsorption of the afterglow emission by trapped charges as an important loss mechanism, leading to a nonlinear scaling of the emission intensity with the crystal size. If circumvented, the emission intensity could be further increased, in persistent luminescent powders, ceramics, and single crystals.

Removal of H2S via hot gas desulfurization demands more advanced and efficient processes to meet the envi-ronmental and economic requirements of modern industry. Hereto, we propose a novel process, termed CO2- assisted Chemical Looping Hot Gas Desulfurization (CCLHGD), that involves alternating H2S-induced sulfuri-zation and CO2-enabled regeneration of a core-shell structured ZrO2-modified Fe2O3 oxygen carrier. Such CCLHGD process can be isothermally implemented at 750 degrees C with Ar-diluted model reactants, i.e., 50 % H2 and 50 ppm H2S for sulfurization and 10 % CO2 for regeneration, wherein all H2S is captured and next released as SO2. Fe2O3 undergoes a stepwise sulfurization (with Fe3O4 and Fe as intermediates) towards iron sulfides, while the latter can be completely regenerated to iron oxides by CO2. The thermally stable ZrO2 in the core-shell structure contributes to resist sintering of the sulfurized iron particles, leading to good regenerability by oxidation with CO2. This work demonstrates an efficient chemical looping scheme for H2S removal, providing new opportunities for hot gas desulfurization.

The spectrally-selective monitoring of doses of UV and visible light is crucial in numerous applications like photodynamic therapy and personal solar UV detection, due to the specific irradiation impact of light with different wavelengths and doses. Herein an approach to design wavelength-specific integrating light dosimeters is demonstrated based on photo-induced redox processes of certain lanthanides in phosphate compounds. Systematic experiments reveal that the reduction process is induced through ligand-to-metal charge transfer excitation while the oxidation process is achieved upon excitation of either the involved hole traps or 4f(N)-4f(N-1)5d(1) transitions of the created divalent dopants. These processes are rationalized in multi-electron energy level diagrams for local electron transfer. The dose and wavelength-dependent redox processes allow for selective UV and visible light dosimetry, and the spectral sensitivity of the dosimeter can be tailored by manipulating the dopant or the host. Particularly, the spectral sensitivity of Ba2.99Eu0.01(PO4)(2) better matches the erythemal action spectrum of human skin than that of currently used benchmark polysulphone dosimeters, making it ideally suitable for personal solar UV radiation monitoring. These findings open the door to designing wavelength-tunable light dosimeters according to the requirements of envisioned applications and are expected to benefit a wide range of luminescent functional devices.

Light sensors are widely used to monitor light intensities, for instance in medical applications, in agriculture or for conservation of art. Most of these sensors are electronic devices that record continuously but applications that only require information of integrated intensities, measured over a long time, could greatly benefit from an integrating dosimeter that does not require a power supply. In this work a wireless and quantitative light dosimeter is presented based on SrAl2O4:Eu2+,Sm3+, a phosphor that exhibits stable energy storage upon exposure to blue and ultraviolet light. It is shown that a forward electron transfer from europium to samarium can be induced under illumination with blue or ultraviolet light while the reverse electron transfer can be achieved by illuminating the phosphors with green to infrared light. This reverse transfer is accomplished through excitation of the divalent samarium and results in bright, green optically stimulated luminescence. The stable energy storage, in combination with the possibility for optical read‐out, makes SrAl2O4:Eu2+,Sm3+ ideally suited to be used as an integrating light dosimeter for monochromatic to broadband light, from the ultraviolet to the near infrared. To demonstrate this, a proof of concept dosimeter was developed in which this phosphor was successfully used to measure average daylight intensities.

The excited manifolds of luminescent materials activated with lanthanide ions and their associated spectroscopies range in complexity from the simplest case of Ce $$^{3+}$$ -doped materials, where only one unpaired electron plays the relevant roles, to the much more complex case of Eu $$^{2+}$$ -doped materials, where many electrons are active in the open-shells and create a variety of problems and opportunities. In this Chapter, a multiconfigurational ab initio approach to fundamental spectroscopic studies of materials with different levels of complexity is discussed.

Glow‐in‐the‐dark materials have been around for a long time. While formerly materials had to be mixed with radioactive elements to achieve a sufficiently long and bright afterglow, these have now been replaced by much safer alternatives. Notably strontium aluminate, SrAl2O4, doped with europium and dysprosium, has been discovered over two decades ago and since then the phosphor has transcended its popular use in watch dials, safety signage, or toys with more niche applications such as stress sensing, photocatalysis, medical imaging, or flicker‐free light‐emitting diodes. A lot of research efforts are focused on further improving the storage capacity of SrAl2O4:Eu2+,Dy3+, including in nanosized particles, and on finding the underlying physical mechanism to fully explain the afterglow in this material and related compounds. Here an overview of the most important results from the research on SrAl2O4:Eu2+,Dy3+ is presented and different models and the underlying physics are discussed to explain the trapping mechanism at play in these materials.

This book serves as a guide to advanced quantum chemical methods for calculating the basic properties of luminescent materials

The performance of persistent phosphors under given charging and working conditions is determined by the properties of the traps that are responsible for these unique properties. Traps are characterized by the height of their associated barrier for thermal detrapping, and a continuous distribution of trap depths is often found in real materials. Accurately determining trap depth distributions is hence of importance for the understanding and development of persistent phosphors. However, extracting the trap depth distribution is often hindered by the presence of a thermal barrier for charging as well, which causes a temperature-dependent filling of traps. For this case, we propose a method for extracting the trap depth distribution from a set of thermoluminescence glow curves obtained at different charging temperatures. The glow curves are first transformed into electron population functions via the Tikhonov regularization, assuming first-order kinetics. Subsequently, the occupation of the traps as a function of their depth, quantified by the so-called filling function, is obtained. Finally, the underlying trap depth distribution is reconstructed from the filling functions. The proposed method provides a substantial improvement in precision and resolution for the trap depth distribution compared with existing methods. This is hence a step forward in understanding the (de)trapping behavior of persistent and storage phosphors.